Computational fluid dynamics investigations of plug-flow for improving anaerobic digestion of high-solid material
Title: Computational fluid dynamics investigations of plug-flow for improving anaerobic digestion of high-solid material
SNIC Project: LiU-compute-2021-38
Project Type: LiU Compute
Principal Investigator: Hossein Nadali Najafabadi <>
Affiliation: Linköpings universitet
Duration: 2021-09-05 – 2022-05-01
Classification: 20306


This study aims to develop a CFD model for the prediction of fluid flow behaviour in a plug-flow reactor. The model will represent the setup, conditions and operation of a newly built experimental reactor, which has been constructed within the BRC-FO1-project and is located at the Swedish University of Agricultural Sciences (SLU). After careful verification and validation, the built simulation model can be used for parametric investigations and analysis of the effects of various operational parameters, such as feeding rate and stirring intensity, on fluid flow in the plug-flow reactor, as well as on performance of the anaerobic digester and process efficiency. The temperature effects on fluid flow behaviour will also be investigated to evaluate how temperature-phased AD may be established in the reactor. This will provide important information for future studies performed with this reactor (e.g. within BRC-FO1-project), since knowledge on temperature distribution is essential for performing studies on its effects on microbial community structure and functions in the reactor. Furthermore, an important output of the CFD study will be the development of a modelling- and simulation- application that can be used to perform necessary simulations prior to the operational parameter changes and evaluate the effect of such parameters. This can lead to improved AD process performance during digestion of high-solid substrates. In addition, since published information on the rheology of plug-flow digester fluids is limited, this study aims to gather data in order to fill this knowledge gap and provide a basis for the CFD modelling. The knowledge from CFD simulations of these lab-scaled plug flow digester is of high value for real scale reactors with the use of dynamic similarity and dimensional analysis of the flow problem. Thus by use of dimensionless numbers, e.g. Reynolds number, the CFD results from lab-scale model will be of relevance to real scale plug-flow digestor. The modelling assumptions and simplifications should however be considered.